checkout/bag url rewrite

config.xml

<config>
  <global>
    <rewrite>
      <mynamespace_mymodule_checkout_cart>
        <from>
        <![CDATA[ #^/checkout/bag# ]]>
        </from>
        <to>/checkout/cart</to>
      </mynamespace_mymodule_checkout_cart>
    </rewrite>
    <models>
      <getready_rewrite>
        <class>Getready_Rewrite_Model</class>
      </getready_rewrite>
      <core>
        <rewrite>
          <url>Getready_Rewrite_Model_Core_Url</url>
        </rewrite>
      </core>
    </models>
  </global>
</config>

Url.php

class Getready_Rewrite_Model_Core_Url extends Mage_Core_Model_Url {
  
  /**
   * Build url by requested path and parameters
   *
   * @param   string|null $routePath
   * @param   array|null $routeParams
   * @return  string
   */
  public function getUrl($routePath = null, $routeParams = null) {
    
    if ( $routePath == 'checkout/cart' ) {
      $routePath = 'checkout/bag';
    }
    
    return parent::getUrl($routePath, $routeParams);
  } 
}